Make the thread queue walk function take a cookie to the callback

and implement a _clear() function to clear out the queue

include/ucore/threadqueue.h

@@ -44,7 +44,7 @@ struct uc_threadmsg{
 /**
  * Callback function for the walk and destroy functions.
  */
-typedef void (*uc_thread_queue_walk_func) (struct uc_threadmsg *msg);
+typedef void (*uc_thread_queue_walk_func) (struct uc_threadmsg *msg, void *cookie);
 
 
 /**
@@ -240,23 +240,40 @@ long uc_thread_queue_length( struct uc_threadqueue *queue );
  * @param queue Pointer to the queue that should be cleaned
  * @param free_func pointer to function that will be called for each item. 
  *  The function must not in anyway interact with the queue.
+ * @param cookie pointer passed back to the uc_thread_queue_walk_func
  * @return 0 on success EINVAL if queue is NULL EBUSY if someone is holding any locks on the queue
  */
-int uc_thread_queue_destroy(struct uc_threadqueue *queue, uc_thread_queue_walk_func free_func);
+int uc_thread_queue_destroy(struct uc_threadqueue *queue, uc_thread_queue_walk_func free_func, void *cookie);
 
 /**
  * Walk the elements of the queue, intended for debugging
  * 
  * The supplied function will be called for each item in the queue, internal queue
  * locks are held while the function is called, so the supplied function must not 
- * interact with the queue, else deadlock occors.
+ * interact with the queue, else deadlock occurs.
  * 
  * @param queue Pointer to the queue to walk
  * @param free_func pointer to function that will be called for each item. 
+ * @param cookie pointer passed back to the uc_thread_queue_walk_func
  *  The function must not in anyway interact with the queue.
  * @return 0 on success 
  */
-int uc_thread_queue_walk(struct uc_threadqueue *queue, uc_thread_queue_walk_func walk_func);
+int uc_thread_queue_walk(struct uc_threadqueue *queue, uc_thread_queue_walk_func walk_func, void *cookie);
+
+
+/**
+ * Clear the queue.
+ * The free_func unless NULL, will be called for each element 
+ * locks are held while the function is called, so the supplied function must not 
+ * interact with the queue, else deadlock occurs.
+ *
+ * @param queue Pointer to the queue to clear
+ * @param free_func pointer to function that will be called for each item, intended to e.g. release memory
+ * @param cookie pointer passed back to the uc_thread_queue_walk_func
+ * @return 0 on success 
+*/
+int uc_thread_queue_clear(struct uc_threadqueue *queue, uc_thread_queue_walk_func free_func, void *cookie);
+
 
 /**
  * @}*/